The present invention relates to a colored golf ball. More particularly, it relates to a color golf ball having soft and good shot feel at the time of hitting and excellent discriminability because of deep and vivid color tone, when used in bad weather or the winter season.
Most of golf balls that are commercially sold have a white appearance. In order to make the golf ball whiter, the cover thereof contains a white pigment such as titanium dioxide or a fluorescent brightener. If the white pigment does not impart sufficient whiteness to the golf balls, the whitened cover is further coated with white paint. Golf balls having a colored appearance other than white appearance, which are called colored golf balls, are also being commercially sold. The colored golf ball has been used because of curiousness or for differentiation from golf balls used by other golfers, but they have not been considered in connection other functions, such as use in bad weather or in the winter season.
The color golf balls, when compared with the golf balls having white appearance, have excellent discriminating value when used in cloudiness, fog or rain conditions, which is often is the case in the mountains where the weather is changeable, or when used on snow or the dormant grass of the winter season. In these situations the colored golf ball seems to have better attributes than the golf balls having a white appearance. On the other hand, since the conventional colored golf balls are produced without taking account of the above points, they exhibit poor shot feel when hit at a low temperature because the impact force at the time of hitting is very large when compared to hitting under usual condition.
The colored golf ball can be obtained by not coating white enamel paint but by coating with colored paint on the surface of the golf ball. Therefore colored golf balls have the problem of appearance such as color shading, which does not occur in the golf balls having a white appearance. Also, when the surface of the colored golf ball is damaged at the time of hitting, its paint layer can peel off, rendering the appearance of the golf ball poor because the difference in the color between the colored paint and the cover layer becomes quite noticeable by the exposure of the underlayer (cover layer).
The color golf balls obtained by introducing an inorganic or organic pigment into the cover composition to color the cover, without coating the cover with colored paint have been proposed. The resulting colored golf balls do not have the problem of the appearance, such as color shading or peeling off. However, excellent discriminability as a new function of the colored golf ball is not sufficient, because the vividness of the color of the cover is not sufficient.
In any case, since conventional colored golf balls have been employed because of curiousness, the need to improve the discriminability of the golf ball for use in bad weather or in the winter season and to solve the problem of the appearance thereof has been neglected.
A main object of the present invention is to provide a colored golf ball having soft and good shot feel at the time of hitting and excellent discriminability because of vivid and deep colored tone, when using in bad weather or winter season conditions.
According to the present invention, the object described above has been accomplished by employing a cover composition containing a specified amount of fluorescent pigment and titanium dioxide, and by adjusting the L*-value of the surface of the golf ball, measured using a color difference meter, to a specified range. Thus, a colored golf ball is provided having a soft and good shot feel at the time of hitting and excellent discriminability, when used in bad weather or winter season conditions.
The present invention provides a color golf ball comprising at least one layer of a core and at least one layer of a cover formed on the core, wherein the outermost layer of the cover contains 3.0 to 7.0 parts by weight of fluorescent pigment and 0.05 to 0.5 parts by weight of titanium dioxide. The cover is coated with one or more layers of a clear coating, and the surface of the golf ball has an L*-value of 50 to 80, measured using a color difference meter.
In the colored golf ball of the present invention, it is preferable that
(a) the surface of the golf ball has an a*-value of 40 to 70 and a b*-value of 70 to 90, measured using a color difference meter, when the fluorescent pigment is an orangish fluorescent pigment, and
(b) the surface of the golf ball has an a*-value of 30 to 60 and a b*-value of 10 to 30, measured using a color difference meter, when the fluorescent pigment is a pinkish fluorescent pigment.
In the present invention, the color difference measurement is conducted by a color-difference-colorimeter, which employs a method of directly reading the tristimulus value and an L*a*b* color specification system, thereby obtaining the L*-value, the a*-value and the b*-value. The L*-value represents lightness, and the a*-value and b*-value represent chromaticity, which is shown as hue and chroma. The surface of the colored golf ball of the present invention has an L*-value of 50 to 80, preferably 60 to 75, measured using a color difference meter. When the L*-value is smaller than 50, the color tone is dark. On the other hand, when the L*-value is larger than 80, the colored tone is pale. Therefore, in both cases, the colored golf ball does not have sufficient discriminability when used in bad weather, or in snow and the dormant grass in the winter season.
The surface of the colored golf ball of present invention has an a*-value of 40 to 70, preferably 45 to 60, and a b*-value of 70 to 90, preferably 75 to 85, measured using a color difference meter, when the golf ball contains an orangish fluorescent pigment, that is, the golf ball has an orangish hue. When the a*-value is out of the range of 40 to 70, and the b*-value is out of the range of 70 to 90, the colored golf ball containing the orangish fluorescent pigment cannot obtain the desired hue, and can not sufficiently obtain a discriminability when used in bad weather, or in snow and dormant grass in winter season. The surface of the colored golf ball of present invention has an a*-value of 30 to 60, preferably 35 to 55, and a b*-value of 10 to 30, preferably 15 to 25, measured using a color difference meter, when the golf ball contains a pinkish fluorescent pigment, that is, the golf ball has a pinkish hue. When the a*-value is out of the range of 30 to 60, and the b*-value is out of the range of 10 to 30, the colored golf ball containing the pinkish fluorescent pigment cannot obtain the desired hue, and can not sufficiently obtain a discriminability when used in bad weather, or in snow and dormant grass in winter season conditions.
In the colored golf ball of the present invention, it is preferable that the golf ball has a deformation amount of 2.90 to 3.60 mm, preferably 2.90 to 3.45 mm, more preferably 3.00 to 3.30 mm, when applying from an initial load of 10 kgf to a final load of 130 kgf on the golf ball, and has a impact force of 950 to 1,200 kgf, preferably 1,000 to 1,150 kgf, when hit at a head speed of 40 m/second by a driver. When the deformation amount is smaller than 2.90 mm, the golf ball is too hard, and the shot feel is poor. On the other hand, when the deformation amount is larger than 3.60 mm, the golf ball is too soft. Therefore the rebound characteristics are degraded, and the shot feel is heavy and poor. When the impact force is smaller than 950 kgf, the shot feel is too light and poor. On the other hand, when the impact force is larger than 1,200 kgf, the impact at the time of hitting is too large, and the shot feel is poor. When playing golf, particularly in the winter season, the shot feel at the time of hitting the golf ball is too hard, as compared to the other seasons, because of the temperature. The colored golf ball of the present invention has a soft and good shot feel, because of softening the ball and reducing an impact force at the time of hitting, in addition to excellent discriminability of the golf ball. Therefore it is easy to play in winter season by using the colored ball of the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.